A novel method has been developed to bias the insertion of structured particles into dense phases during grand canonical and Gibbs ensemble Monte Carlo simulations. The method biases the orientation rather than the position of a trial insertion. The method has been shown to increase the acceptance rate by a factor of two. It has been used in Gibbs ensemble simulations of TIPS2 and TIP4P water at and above ambient temperature, and points on a coexistence curve have been simulated. The TIP4P model has been shown to reproduce experimental data much more closely than the TIPS2 model.